Radiosonde humidity element



March 30, 1943;

B. R. SHAW RADIOSONDE HUMIDITY ELEMENT Filed July 18, 1941 Patented Mar. 30, 1 943 RADIOSONDE HUMIDITY ELEMENT Benson Russell Shaw, Washington, D. (7., assignor Q to Washington Institute of Technology, 1110., Washington, D. 0., a corporation of Delaware Application July 18,1941, Serial No. 403,044

(creel-4s) v there is an annular groove 3, within which the 3 Claims.

This invention relates, broadly, to devices or systems for varying an electric current in accordance with a variable factor and, more particularly, relates to the humidity-responsive system of a radiometeorograph, by which the changing humidity of the air is caused to vary an electric current, thereby permitting an indication of humidity changes to be secured.

by an adhesive or othermaterial.

ends of the separate hairs are received and held The lower button 2 is adjustably attached to a fixed sup port 4 while the upper button is attached to the arm of a lever B which is attached to and carried by a shaft 1. The fixed support 4 is carried by a wall member I I and the shaft 1 extends through the wall member, all of the parts heretofore described being on the same side of the wall member. A rain shield ll, comprising an arcuate-shaped member formed preferably of a plastic, is attached to wall directly above humidity element l, lever 6 and shaft 1.

Referring to the drawing, in which similar 7 and Fig. 4 is a partial view of the humidity-responsive device illustrated in Fig. 1, showing particularly the attachment of the hairs to the supports therefor.

In radiometeorographs it is usual to provide an element, one of the physical characteristics of which, such as overall length, changes with variations in the humidity of the surrounding air, together with means for causing such physical changes to be transformed into variations of an electric current. The present invention provides an improved apparatus of this type. t

In Fig. 1 of the drawing there is disclosed a humidity element I comprising a-cylindrical arrangement of a plurality of hairs or other elements which change in length in accordance with changes in the humidity of the surrounding air', the hairs or other elements being separated from each other to insure better circulation of air therebetween. At each end of the cylindrical element thehairs are supported on a disk-like button 2, shown in Fig. 4, having any desired cross-sectional shape, in the periphery of which On the opposite side of the wall member ID the shaft'l is elongated and extends axially through an elongated, cylindrical housing 'II which is received and supported within an opening in the wall Ill. The end wall 10 of the housing l5 adjacent the wall is provided with a double-tapering opening [6 which just fits the shaft 1, thusproviding a wedge-shaped bearing for the shaft. At its opposite end the housing 15 is open and receives a closure!!! which is also provided with a double-tapering opening 2| which justreceives and supports the shaft 1.

Rigidly connected to the. inner end of shaft 1, which is the end thereof opposite the lever 6, is

a depending, straight arm 30 and a second arm 3|, the lower end of which is in the vertical plane of the shaft 1 and the arm 30 and is approximately parallelto and under the shaft and at right angles to the depending arm. Thev arm 30 is preferably made of fiat, flexible material in the edge of an arcuate member 35, which is concentric with the shaft 1 and about which are wound a plurality of turns of wire 36 forming a resistance coil,'-the member 35 being supported by a similarly shaped part 31, it being noted -The periphery of the wheel or roller 33 engages that the support 31 is of less transverse extent than the resistance member 35 in order to permit the contact roller 33 to engage the edge of the resistance member.

The contact wheel or roller 33 is formed with v a groove 34 midway between its ends, the bottom of this groove being flat and of sufficient extent axially of the roller to just receive the edge of the resistance winding 36 which is wound about support 35. At each end of the groove the material of the roller extends approximately at right angles to the bottom of the groove for a short distance, thereby being in face-to-face' contact with both the upper and lower faces of the resistance winding adiacent the edge thereof. By reason of this structure the roller and the resistance winding me in engagement over the edge of the contact with the outer parts of the upper and lower surfaces thereof, thus providing an improved wiping contact.

A spring 40 is connected between an upper part of the arm 30 and a fixed part 4| on the wall II and normally urges the arm to a position in which the contact roller is approximately at the center of the resistance, being held there against the force of the spring by tension exerted by the humidity-responsive element I. A second spring 42 is connected between the extremity of the rightangled arm 3! and the depending arm 30 and constantly urges the roller 33 into engagement with the resistance in the manner described.

The contact arm 30 is connected to an electrical circuit by a lead 45, and the two ends of the resistance winding 36 are connected to electrical circuits by leads 46, 41. The particular circuits to which these parts are connected, and the effect on these circuits of variation of the amount of resistance 35 therein by reason of movement of the arm 30 is not of importance here and forms no part of this invention.

Means are provided by the invention for simultaneously covering the described structure, to protect it from dust and otherwise, and preventing the contact wheel from becoming entirely removed from the edge of the resistance member. Such means comprise a cup-shaped cover 50, which is preferably rectangular in shape, as shown by dotted lines in Fig. 1, being provided with side walls and a bottom 52. This shield covers all of the described apparatus on the side of the wall to opposite to that on which the humidity-responsive device is mounted and is supported there by any suitable means such, for example, as by engagement of the inner periphery of its free edge with the wall of a rectangular flange 53 formed on the wall in. This cup-shaped shield is so formed and proportioned that the inner face 54 of the bottom wall 52 thereof is spaced from the outermost periphery of the contact roller 33 by a distance which is less than the radial distance between such outermost periphery and the bottom of the groove 34 in the roller. Thus, if the roller is moved away from the resistance 36, as by a shock or jar, it will be stopped in such movement by engagement of its outer periphery with the wall 54 before it can move completely away from the resistance.

In the operation of the device, the adjusting means at support 4 will be so adjusted as to maintain the humidity-responsive element l, lever I and shaft 1 in such a position that the spring 4| will cause the contact roller 33 to occupy a predetermined position on the resistance winding 80, which will preferably be near the center thereof. Any variation in the humidity of the surrounding air will cause the overall length of the element I to be shortened or lengthened, thereby causing the lever B to be moved to rotate shaft I and causing the arm ll and roller 43 to be moved in one direction or the other with respect to resistance 45. It will be seen that shortening of the humidity element will cause it to exert a direct pull on the lever 6, while if the humidity change is such that the overall length of the element t is increased, the spring 40 will cause the arm 30 to move in the manner described.

While I have described and illustrated one embodiment of my invention, it will be apparent to those skilled in the art that further embodiments and modifications may be made and practiced without departing in any way from the spirit or scope of the invention, for the limits of which reference must be had to the appended claims.

What is claimed is:

1. An apparatus for varying the resistance of an electric circuit in accordance with changes in the humidity of the surrounding air, comprising a device the overall length of which is varied by changes in the humidity of the air, one end of said device being connected to a fixed support, a lever arm connected to the other end of said device, said lever arm being fixed on a shaft, an arm fixed to said shaft and having a roller at the extremity thereof which is formed with a groove extending entirely thereabout between the ends thereof, an arcuate resistance element arranged concentrically with said shaft and having an edge portion engaging said roller and received within the groove therein, the parts of said roller defining the groove therein being so formed that contact between the roller and the edge portion of the resistance element is maintained during movementof the roller away from the edge portion, a cup-shaped member covering said shaft, arm, roller and resistance and having a bottom wall spaced from the outer peripheral edge of the roller by a distance less than the depth of the groove in the roller, means urging the arm and roller to a predetermined position with respect to the resistance element, and an electric circuit including the arm and the resistance element.

2. An apparatus according to claim 1, in which the groove in the roller is defined by a relatively fiat bottom and walls extending approximately at right angles thereto, within which the edge portion of the resistance element is received.

3. An apparatus according to claim 1, in which the groove in the roller is defined by a relatively fiat bottom and walls extending approximately at right angles thereto and spaced apart by a distance approximately equal to the thickness of the edge Portion of the resistance element, within which the edge portion of the resistance element is received.

BENSON RUSSELL SHAW. 

